1. Technical Field
The present invention relates to drivers, electronic devices, and the like.
2. Related Art
Display devices (liquid-crystal display devices, for example) are used in a variety of electronic devices, including projectors, information processing apparatuses, mobile information terminals, and the like. Increases in the resolutions of such display devices continue to progress, and as a result, the time a driver drives a single pixel is becoming shorter. For example, phase expansion driving is used as a method for driving an electro-optical panel (a liquid-crystal display panel, for example). According to this driving method, for example, eight source lines are driven at one time, and the process is repeated 160 times to drive 1,280 source lines. In the case where a WXGA (1,280×768 pixels) panel is to be driven, the stated 160 instances of driving (that is, the driving of a single horizontal scanning line) is thus repeated 768 times. Assuming a refresh rate of 60 Hz, a simple calculation shows that the driving time for a single pixel is approximately 135 nanoseconds. In actuality, there are periods where pixels are not driven (blanking intervals and the like, for example), and thus the driving time for a single pixel becomes even shorter, at approximately 70 nanoseconds.
With a shorter pixel driving time as mentioned above, it is becoming difficult for the amplifier circuits to finish writing the data voltages within the required time. A method that drives an electro-optical panel through capacitor charge redistribution (called “capacitive driving” hereinafter) can be considered as a driving method for solving such problems. For example, JP-A-2000-341125 and JP-A-2001-156641 disclose techniques that use capacitor charge redistribution in D/A conversion. In a D/A conversion circuit, both driving-side capacitance and load-side capacitance are included in an IC, and charge redistribution occurs between those capacitances. For example, assume such a load-side capacitance of the D/A conversion circuit is replaced with the capacitance of the electro-optical panel external to the IC and used as a driver. In this case, charge redistribution occurs between the driver-side capacitance and the electro-optical panel-side capacitance.
The capacitive driving that thus uses charge redistribution has a problem in that the data voltage accuracy lowers as compared with when using the amplifier circuit, which is capable of supplying charges freely. As a driving method for solving such a problem, a method (called “voltage driving” hereinafter) can be considered that further outputs highly-accurate data voltage using the amplifier circuit after starting high-speed driving through the capacitive driving. In this case, a D/A conversion circuit is provided that outputs a voltage corresponding to tone data to the amplifier circuit.
However, a problem arises in that, in the case where it takes long time for the output of the D/A conversion circuit (input of the amplifier circuit) to settle at the voltage corresponding to the tone data, it will also take long time for the output of the amplifier circuit, which receives the output of the D/A conversion circuit, to settle at a data voltage. For this reason, there is a possibility that highly-accurate data voltage cannot be written within pixel writing time.